(3 of 3)
Some U.S. officials privately complain that many Mexican police aid the Zetas. And other potential microcartels are proliferating on the U.S.'s doorstep: in the Tijuana--San Diego corridor, police are dealing with a gang known as Narco-Juniors, a group of affluent juvenile delinquents recruited as hit men in the 1990s by the Tijuana drug cartel. Authorities in the Juarez--El Paso corridor, meanwhile, report a growing presence of the Mara Salvatrucha, a machete-wielding gang that has terrified Central America in recent years. The threat from groups like the Zetas may persist for years. "This is like any instance of monopoly busting," says Jorge Chabat, a professor of international relations at the Center for Economic Research and Teaching in Mexico City. "Once the little guys are let into the business, it's hard to push them out again." --With reporting by Cathy Booth Thomas/Laredo, Dolly Mascareñas/ Mexico City and Elaine Shannon/ Washington